3 inches is perfect ...

F roots in about a week ...

take a one gal pot.. put some dampened potting media in it ... and take six 8 inch cuttings from the good ones ... and put it in shade..

by fall.. you ought to have 4 to 6 rootings ... this gives it time to grow a nice root mass ...

if the oddball out.. doesnt get its act together by fall.. get rid of it.. and plant the replacements you rooted ... and give away excess as a gift ...

ken

I have an old forsythia that is sort of in the way now that I've redesigned an area and made a walkway. When it gets too large, I cut it back to basically nothing. Cutting all the stems down to a couple of inches leaving no leaves.

As Ken said, the 3" you took yours down to is just fine

I last did this in the fall but, quite honestly, I don't even have a schedule - I just do it when the bush starts to get it the way.

Anyway, this spring I didn't see any new growth for ages and thought I had done it in. But it's come back nicely now

just went out and took a pic for you -